There are some issues with everyone having their own LB when it comes to content creation and game balance.

For example, if SE is developing bossfight mechanics they need to take the LBs into account. Core mechanics of fights might become trivialised by personal LBs otherwise which would lead to broken encounters. To counter this they would have to do one of two things:

1. Make personal LBs substantially weaker than party LBs. The issue with this option is it turns a personal LB into little more than just another powerful CD.

2. Make it LBs are required as part of encounter mechanics. The issue with this is that if you have other players screw up you either wipe or have to wait while everyone recharges their LBs from scratch. This would cause a lot of problems in PUGs in particular.

The first option seems kind of pointless. Its just another cd with a mechanic that makes it harder to use effectively. In the end in the first case most dps would use it the moment it fills and Tanks and Healers would save it for major damage spikes. Pretty much what happens with CDs now but without a reliable recharge mechanic.

The second option would be too problematic to be practical. It would inevitably cause many problems in Pugs and Duty Finder and lead to a lot of ingame arguments and conflict.

From my point of view, while it sound like a cool idea, when you look at the practical application of the idea it's very flawed.